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Michael Ross

Generation of Field Calculations Volumes

Can this tool all be used to generate a volume for calculating the electric field? i.e. to encapsulate one object into another, and then using it to determine the electric field at the surface of an object. For example, a sphere inside of another sphere, and calculating the electric field intensity inside of the volume between the objects?

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    AbderRahman N Sobh

    For the specific sphere-inside-of-sphere case, we actually already provide DDSCAT's preset "Concentric Ellipsoid" shape option for use within either nanoDDSCAT ( or the nanoDDSCAT+ workflow (

    In general, a user has to delineate each shape as a separate object so that DDAConvert can assign a different dielectric number to each shape. With respect to your request, there are three possible cases I think you might be referring to simulating so I'll cover all of them. 

    Case1: Similar to the "Concentric Ellipsoids" option, two general shapes that are contained within each other and are directly in contact. The user need not generate a shell and a central shape, but can actually just draw the first object and literally place the second object in side of it. DDAConvert already handles overlapped shapes and will allocate the points to one object or there other. By default DDAConvert allocates overlapped points to the smallest shape (this behavior can be inverted if desired).

    Case2: Two concentric shapes that are separated by a spacing. In this case, the user will indeed have to draw a shell and place the second object inside of it. The spacing will take on the refractive index of the Ambient Medium when run via nanoDDSCAT.

    Case3: Two concentric shapes separated by a spacing which is to have a different refractive index from the ambient medium. This setup must be prepared using three shapes in total. The three separate shapes would correspond to the outer shell, the volume in between the shells, and the inner core. Again, overlapping can be used in conjunction with DDAConvert's capabilities to simplify this process to some extent. However, this time it is a bit trickier because overlaps between all three shapes can cause issues so the maximum overlaps should be between two shapes only (i.e. on the edges between the shapes is a safe overlap area).


    Additionally, I recommend using the nanoDDSCAT+ workflow for doing this since we provide an environment for drawing the 3D shapes as well as preparing them properly during the export process so that the files are guaranteed to work in DDAConvert.

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